The objective of this project is to characterize dose-response relationships and toxicity of primaclone and oxymethalone administered by dosed feed to rats and mice in 14-day repeated-dose, 90-day subchronic, and 2-year chronic studies. Animals will be treated ad libitum for 14 and 90 days or 2 years. At the end of each study, all animals will be given gross and microscopic histo-pathologic evaluations. Hematology, clinical chemistry, and sperm morphology/vaginal cytology will be performed in the 90-day study. The results of each study will be used by NTP to establish doses to be used in the next study (i.e. the 14-day results for the 90-day study; the 90-day results for the chronic study).